azadeh bazrmanesh; Mostafa Tarkesh; Hossein Bashari; Saeid Poormanafi
Abstract
In order to model the potential habitat of Bromus tomentellus Boiss and study the effect of climate change on the habitat of this species in Isfahan province method of modeling maximum entropy (MAXENT) were used. The species event data were determined by random categorization method using field visits ...
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In order to model the potential habitat of Bromus tomentellus Boiss and study the effect of climate change on the habitat of this species in Isfahan province method of modeling maximum entropy (MAXENT) were used. The species event data were determined by random categorization method using field visits and geographic information system including 60 rangeland locations as educational points. Also, 20 points of occurrence were surveyed using GPS in the western region of Isfahan as points of assessment. 22 environmental layers including 3 physiographic variables and 19 climate variables derived from temperature and rainfall were used in the modeling process. Using by Maxent, the relationship between species incidence and environmental factors was determined. Then, the effect of climate change using cluster variables of CCSM4 general circulation model was evaluated under two scenarios RCP2.6 (optimistic) and RCP8.5 (pessimistic) on geographic distribution of Br.tomentellus Boiss. Regarding the photo curves, the specie’s behavior relative to the environmental variables of Br.tomentellus Boiss in the range of 2500 to 3500 altitudes, slope 10 to 30 degrees, annual precipitation is 240 to 260 mm and the average temperature is 8 to 10 ° C are more likely to occur. The habitat of the species studied during the two periods of 2050 and 2070, it was observed that under the optimistic scenario, 46.1 square kilometers to the appropriate level of the habitat of the Br.tomentellus Boiss is increased and under a pessimistic scenario, about 35.74 km2 is reduced from the appropriate level of habitat of this species.
Ghader Karimi; hasan Yeganeh; Masoomeh Abassi Khalaki; mehdi moameri; Hadi Afra
Abstract
To evaluate the vegetative and productive characteristics and forage utilization by livestock at different stages of Bromus tomentellus Boiss.Phonology, this experiment was carried out during five years in Kordan Rangeland of Alborz province rangelands. So starting the grazing season and livestock entering, ...
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To evaluate the vegetative and productive characteristics and forage utilization by livestock at different stages of Bromus tomentellus Boiss.Phonology, this experiment was carried out during five years in Kordan Rangeland of Alborz province rangelands. So starting the grazing season and livestock entering, any remaining amount of forage grazing was harvested until a month intervals, and utilization rate was determined by subtraction between harvested forage and fenced plot forage. Finally, in order to study the effect of harvest months on the production and utilization of specie under investigation in the study area, data were analyzed. In overall, the results of this study were showed that highest production was belong to third and fourth years and least production was belong to first year. The utilization changes were similar to production changes. In addition, growth and production period Bromus tomentellus Boiss.was spring. The growth and production this plant was maximum in April and then reduced in July. The forage of this plant in May and June has been strongly grazing in the study area. In July the utilization rate this plant was decreased. It seems that the complete growth stages, this species have a woody and livestock grazing has less on it. Thus reduce the amount consumed by livestock.
